This application claims the priority of German Patent Application No. DE 102 13 466.9 filed Mar. 26, 2002, which is incorporated herein by reference.
The invention relates to a projectile body having a groove-shaped recess, in which a guide band is disposed.
In large-caliber tank projectiles, established technical requirements often stipulate the use of relatively wide guide bands comprising plastic or copper. It has been seen, however, that wide plastic guide bands can be destroyed because of the high surface pressure accompanying the passage of the respective projectile body through the gun barrel, and therefore cannot perform their intended function. In particular, when guide bands are destroyed, the seal against the propellant gases acting on the rear of the projectile body is inadequate, so the gases can flow past the projectile body in the barrel.
In the use of wide guide bands (i.e., guide bands whose width is xe2x89xa730 mm) made of copper or a copper alloy, the rear seal is usually adequate, but the use of these materials frequently results in an undesired copper plating of the inside surface of the gun barrel. While methods of removing copper are known for narrow copper bands (that is, copper bands whose width is  less than 15 mm), the Applicant in unaware of the methods being applicable to wider guide bands. The applicability of these methods would have to be determined through time-consuming experiments.
DE 198 18 411 A1 discloses a projectile body having a groove-shaped recess for a guide band, the band comprising at least two partial guide bands that are disposed one behind the other in the direction of the projectile longitudinal axis. The first partial band, which faces the bottom of the projectile, comprises soft iron, while the second partial guide band is made of copper. The cited application gives no indication of how to resolve the aforementioned problems associated with wide plastic or copper guide bands.
It is the object of the invention to provide a projectile body having a wide guide band, which is not destroyed when the projectile body passes through the gun barrel and does not cause notable copper-plating of the barrel.
According to the invention, this object generally is achieved by a projectile body having a groove-shaped recess formed in an outer circumferential surface, and a guide band disposed in the groove shaped recess; and wherein: the guide band comprises at least two partial guide bands that are disposed one behind the other in the direction of the longitudinal axis of the projectile body; the first partial guide band, which faces the projectile base, comprises copper or a copper alloy, and its length is smaller than the length of the second partial guide band, which adjoins a front edge of the first partial guide band; the second partial guide band includes a plastic body and a metal sheet support, which is disposed between the plastic body and a groove base of the recess of the projectile body, and is connected in a non-positive lockup to the plastic body; and the second partial guide band includes at least one hollow space that is open to the groove base of the recess of the projectile body. Further, especially advantageous, embodiments of the invention are disclosed and discussed.
The invention is based on the concept of assembling the guide band from two partial guide bands, with the relatively narrow, first partial band, which faces the rear or base of the projectile, comprising copper or a copper alloy and providing a seal against the propellant gases acting on the projectile rear under high pressure. The width of the first partial guide band is selected to prevent notable copper plating. The second, considerably wider partial guide band, which performs the task of actually supporting the projectile body in the gun barrel, essentially comprises plastic, and includes at least one hollow space, which lends it adequate deformation reserves with respect to the high surface pressure acting on the guide band when the projectile body passes through the barrel.
To ensure that the second partial guide band is sufficiently stable, a metal sheet support that faces the groove base of the projectile recess is connected to the plastic body in a non-positive lockup, preferably through injection molding. The hollow space of the second partial guide band can be formed simply by bending the metal sheet support in the region of the hollow space so that it arches toward the outside guide-band surface, then injecting plastic onto the outside of this arched region. This simultaneously establishes the geometry and the position of the hollow space in a simple, low-cost manner.
An advantageous measure for inserting the two partial guide bands as a unit into the recess of the projectile body involves embodying the metal sheet support of the second partial guide band such that it protrudes laterally past the plastic body, so the first guide band can likewise be secured to the sheet support.
Soft iron, which is easily deformed, yet withstands the pressure exerted during the injection of the guide band, has proven advantageous as the material for the metal sheet support. Other metal alloys that are compatible with the projectile body and the copper guide band (electrochemical series) are also acceptable, however.
Further details about and advantages of the invention ensue from the following exemplary embodiment, which is explained in conjunction with figures.